Watch case

ABSTRACT

The invention relates to a watch case comprising a case middle ( 16 ), a bezel ( 18 ) mounted so that it can turn on the middle and defining between them an annular chamber ( 36 ) and a gap ( 40 ) open towards the outside of the case, a glass ( 22 ) mounted in sealed fashion on the bezel, a seal ( 42 ) inserted between the bezel and the middle and arranged in said chamber ( 36 ). According to the invention said seal comprises a ring ( 44 ) of annular shape made of a material of the highly elastically deformable type, of annular shape, and the cross section of which comprises two lips ( 44   a ), one bearing against the bezel ( 18 ), the other against the case middle ( 16 ), and a compression member ( 48 ) arranged in said chamber on the side of the gap, inserted between and collaborating with said lips in order to compress them against the bezel and against the case middle, respectively.

The invention relates to the field of sealed watch cases. It relatesmore particularly to a case provided with a rotary bezel, of the typeoften used in subsea diving watches. The rotary bezel allows a mark tobe brought to face the hands, especially to define a maximum dive time.

Obviously, watches intended to be immersed in water need to be equippedwith a sealed case. This quality is obtained by virtue of the presenceof seals arranged between the constituent parts of the watch case,namely: the bezel, the case middle, the case back and the glass whichthus, together, form a housing protecting the movement.

In watches equipped with a rotary bezel the latter is often arranged onthe case middle, around the glass, but entirely outside the housing. Thebezel can thus turn freely, but is a relative distance away from thehands. The indications it bears can sometimes not be clearly visible. Inaddition, as they are not protected, their legibility may deteriorateover time.

In order to alleviate this drawback it has been proposed to produce acase in which the bezel carries the glass and is mounted to turn on themiddle, with the interposition of an O-ring seal.

Unfortunately, because the seals used have a very large ratio relatingtheir perimeter and the diameter of their cross section, localdeformations may be generated as the bezel is turned. As a result, thequality of the contact between the seal and the walls of the middle andof the bezel is lessened and the sealing may be affected.

In addition, it is problematical to have a seal that allows the bezel tobe rotated easily at a pressure close to atmospheric pressure while atthe same time remaining sealed at great depths.

It is an object of the present invention to alleviate these drawbacks byproviding a watch case equipped with a rotary bezel that can be turnedwith ease and whose sealing remains good, even at high pressure.

More specifically, the invention relates to a watch case comprising acase middle, a bezel mounted so that it can turn on the middle anddefining between them an annular chamber and a gap open towards theoutside of the case, a glass mounted in sealed fashion on the bezel, aseal inserted between the bezel and the middle and arranged in saidchamber.

According to the invention, the seal comprises:

-   -   a ring of annular shape made of a material of the highly        elastically deformable type and the cross section of which        comprises two lips, one bearing against the bezel, the other        against the case middle; and    -   a compression member arranged in said chamber on the side of the        gap, inserted between and collaborating with the lips in order        to compress them against the bezel and against the case middle,        respectively.

The lips are connected to one another by an intermediate part. They arearranged in such a way as to form an acute angle between them. Thechamber is defined by lateral, upper and lower walls. The lips have, attheir free end, a contact surface intended to bear against the lateralwalls of the chamber, while the intermediate part is flat and hugs thelower wall of the chamber. For sealing to be ensured it is necessary forthe gap not to be filled.

The compression member comprises an annular spring placed directly incontact with the lips. Advantageously, this spring has regular waveforms distributed on either side of a circle of a diameter more or lessequal to the mean diameter of the chamber, the wave forms being bentabout the line formed by the mean circle, the angle of the bend beingslightly greater than or equal to the angle formed by said lips. Thisspring may advantageously be made of stainless steel.

The compression member may furthermore comprise a positioning ringinserted between the spring and one of the walls of the chamber. It isadvantageously arranged facing the bezel and comprises positioning studsresting against it in such a way as to keep the intermediate partbearing against a wall of the chamber.

The invention also relates to a seal for a watch. Advantageously, itcomprises a ring of annular shape made of a material of the highlyelastically deformable type, the cross section of which comprises twolips, and a compression member arranged between the lips andcollaborating with them in order to compress them. The compressionmember comprises an annular spring placed directly in contact with thelips and a positioning ring collaborating with the spring in order tohold it in place.

Other features of the invention will emerge from the description whichwill follow, given with reference to the attached drawing, in which:

FIG. 1 is a simplified view in cross section of the elements of a watchcase according to the invention,

FIG. 2 shows, on a larger scale, the structure exhibited by the case ofFIG. 1 at the interface between the bezel and the middle, without theseal at a and with it at b, and

FIGS. 3, 4 a and 4 b illustrate details relating to the seal that thecase according to the invention comprises.

FIG. 1 depicts, in part, a sealed watch case 10 according to theinvention, having a lower face 12, intended to be in contact with thewearer's arm, and an upper face 14 where the means displaying the timeare visible. This case essentially comprises:

-   -   a case middle 16 of annular shape delimiting the volume in which        the various members of the watch lie,    -   a bezel 18 mounted so that it can be turned on the middle 16,    -   a case back depicted schematically as 20 and closing the watch        case 10 on its lower side 12, and    -   a glass 22 fixed in a sealed manner to the bezel 18, closing the        watch case on its upper face 14, and thus allowing the display        means borne by the movement to be seen.

More specifically, the back 20 is fixed to the middle 16, generally byscrewing or by any means known to those skilled in the art, a seal beinginserted between them. The middle 16 has a structure arranged in such away as to allow a watch movement to be fitted. It also comprises a flatsurface 24 and a cylindrical surface 26 for positioning a flange 28.

The flange 28 is fixed to the case middle by screws, depictedschematically by their centerlines 30. It positions and guides the bezel18, thus allowing it to turn on the middle 16.

The glass 22 may be fixed to the bezel 18 by bonding or by insettingwith the interposition of a seal, or using any means known to thoseskilled in the art.

In order to seal the case at its interface between the case middle 16and the bezel 18, these two components are shaped in such a way as todefine an annular chamber 36 exhibiting two lateral walls 36 a and 36 bformed by the middle 16 and the bezel 18 respectively, an upper wall 36c formed by the bezel 18 and a lower wall 36 d essentially formed by thecase middle 16.

The chamber 36 is connected to the outside of the case 10 by a gap 40.

As can be seen in FIG. 2 b, the chamber 36 acts as a housing for a seal42 comprising a ring 44 with two lips 44 a, advantageously made ofpolyurethane with a Shore A hardness of the order of 20 to 30, and acompression member 46.

The ring 44 is annular and its cross section has the overall shape of aU. The lower branch of the U constitutes an intermediate part 44 bconnecting the two lips 44 a. The width of the U, at its base, is lessthan that of the chamber 36, whereas the lips 44 a, which constitute thelateral branches of the U, form between them an acute angle of the orderof 5° to 15°. At their free end, they have a contact surface intended tobear against the walls of the chamber, leaving the gap 40 free. Thesecontact surfaces for contact between the lips 44 a and the lateral walls36 a and 36 b of the chamber 36 are continuous, which means that theseal at the interface between the case middle 16 and bezel 18 isensured.

The intermediate part 44 b is flat and hugs the lower wall 36 d of thechamber 36. A space 48 defined between the branches of the U is thus indirect communication with the outside of the watch case 10, via the gap40.

The compression member 46 is housed inside the space 48. Thiscompression member consists of an annular spring 50 placed directly incontact with the lips 44 a and of a positioning ring 52 inserted betweenthe spring and the upper wall 36 c of the chamber 36.

As illustrated in FIG. 3, the annular spring 50 is in the form of a bandof more or less constant width forming regular wave forms arranged oneither side of a circle of diameter D more or less equal to the meandiameter of the chamber 36. The spring 50 is obtained from a strip ofstainless steel that is chemically machined.

The wave forms are bent in a V-shape on either side of the lineconstituting the diameter D. The angle formed is slightly larger thanthe angle formed by the lips 44 a so that, when it is fitted, it forcesthe free ends of the lips 44 a against the walls 36 a and 36 b of thechamber. This angle typically lies between 10° and 20°. Its vertex isrounded. This configuration means that the spring 50 has greatelasticity.

At atmospheric pressure, the pressure applied by the spring 50 to thering 44 makes it possible to control the torque needed to turn the bezel18 and ensure contact of the lips 44 a over the entire perimeter of thewalls 36 a and 36 b.

The positioning ring 52 depicted in FIGS. 4 a and 4 b has the same meandiameter as the ring 44. It is placed in contact with the spring 50,facing the bezel 18, and has positioning studs 58 resting against thebezel 18 so as to keep the spring 50 in contact with the lips.

The studs 58 are of cylindrical shape and have a flat surface intendedto be in contact with the bezel. The height of the assembly formed bythe ring 52 and by the studs 58 is equal to the distance separating thebezel 18 from the annular spring 50. The latter is thus precisely heldin place while the bezel 18 slides over the studs 58 when it is turned.

When the watch is submerged, the chamber 48 is connected to the externalsurroundings by the gap 40 and, by virtue of the fact that thepositioning studs 58 do not occupy the entire chamber 48, this chamberis at the same pressure as the external surroundings. The water thencompresses the positioning ring 52 which presses against the seal 42 andfirmly presses the lips 44 a against the walls of the chamber 36. Thus,the higher the external pressure, the more firmly the lips 44 a arepressed against the walls 36 a and 36 b of the chamber. Under theseconditions, the friction forces then created between the lips 44 a andthe watch case 10 make any turning of the bezel 18 impossible. The bezelis therefore locked during a dive, and this enhances safety.

In deep water, the diver breathes a gaseous mixture containing helium orhydrogen. These light gases may enter the watch case. As the diverreturns towards the surface, the external pressure may decrease morerapidly than the pressure inside the watch case. If there is no valveprovided for regulating this overpressure, the glass may be expelledfrom its housing. With a case according to the invention, such a valveis not needed. This is because, by virtue of the shape of the lips 44 a,the gas contained inside the case 10 can escape freely.

In other words, the watch case thus produced is perfectly sealed whenthe external pressure exceeds the internal pressure, and it allows thegas it contains to escape when the internal pressure exceeds theexternal pressure.

A sealed watch case provided with a rotary bezel the sealing of which isparticularly good is thus obtained. Furthermore, this good sealing isnot achieved at the expense of the ease with which the rotary bezel canbe turned.

The case as described may, of course, be varied in numerous ways withoutin any way departing from the scope of the invention. Thus, the chamber36 could have a cross section other than a rectangular one. In addition,the seal could be orientated differently with, for example, the lips incontact with the upper 36 c and lower 36 d walls while the intermediatepart would be in contact with the lateral wall 36 a formed on the bezel18.

The means of assembling the bezel 18 with the case middle 16 could alsobe modified considerably. The moving interior part could occupy a fargreater amount of space so as to allow a maximum amount of informationto be displayed and thus offer better conditions for reading thisinformation.

1. A watch case comprising a case middle (16), a bezel (18) mounted sothat it can turn on the middle and defining between them an annularchamber (36) and a gap (40) open towards the outside of the case, aglass (22) mounted in sealed fashion on the bezel, a seal (42) insertedbetween the bezel and the middle and arranged in said chamber (36),characterized in that said seal comprises a ring (44) of annular shapemade of a material of the highly elastically deformable type and thecross section of which comprises two lips (44 a), one bearing againstthe bezel (18), the other against the case middle (16), and acompression member (48) arranged in said chamber on the side of the gap,inserted between and collaborating with said lips in order to compressthem against the bezel and against the case middle, respectively.
 2. Thewatch case as claimed in claim 1, characterized in that said chamber(36) is defined by lateral, upper and lower walls, the lips (44 a) areconnected to one another by an intermediate part (44 b) and are arrangedin such a way as to form an acute angle between them, said lips having,at their free end, a contact surface intended to bear against the wallsof said chamber without said gap being filled.
 3. The watch case asclaimed in claim 2, characterized in that said intermediate part (44 b)is flat and hugs the lower wall of the chamber (36), said lips bearingvia their contact surface against the lateral walls.
 4. The watch caseas claimed in claim 2, characterized in that the compression member (46)comprises an annular spring (50) placed directly in contact with thelips (44 a).
 5. The watch case as claimed in claim 4, characterized inthat the annular spring (50) has regular wave forms distributed oneither side of a circle of a diameter more or less equal to the meandiameter of said chamber, said wave forms being bent about the lineformed by said circle, the angle of the bend being greater than or equalto the angle formed by said lips.
 6. The case as claimed in claim 4,characterized in that said spring is made of stainless steel.
 7. Thecase as claimed in claim 4, characterized in that said compressionmember comprises, in addition, a positioning ring (52) inserted betweensaid spring and one of the walls of the chamber.
 8. The watch case asclaimed in claim 7, characterized in that the positioning ring (52) isarranged facing the bezel (18) and comprises positioning studs (58)resting against said bezel in such a way as to keep the intermediatepart bearing against a wall of said chamber.
 9. A seal for a watch,characterized in that it comprises a ring (44) of annular shape made ofa material of the highly elastically deformable type and the crosssection of which comprises two lips (44 a), and a compression member(48) arranged between the lips and collaborating with them in order tocompress them.
 10. The seal as claimed in claim 9, characterized in thatsaid compression member comprises an annular spring (50) placed directlyin contact with the lips (44 a) and a positioning ring (52)collaborating with the spring in order to hold it in place.
 11. Thewatch case as claimed in claim 3, characterized in that the compressionmember (46) comprises an annular spring (50) placed directly in contactwith the lips (44 a).
 12. The case as claimed in claim 5, characterizedin that said spring is made of stainless steel.
 13. The case as claimedin claim 11, characterized in that said spring is made of stainlesssteel.
 14. The case as claimed in claim 5, characterized in that saidcompression member comprises, in addition, a positioning ring (52)inserted between said spring and one of the walls of the chamber. 15.The case as claimed in claim 6, characterized in that said compressionmember comprises, in addition, a positioning ring (52) inserted betweensaid spring and one of the walls of the chamber.
 16. The case as claimedin claim 11, characterized in that said compression member comprises, inaddition, a positioning ring (52) inserted between said spring and oneof the walls of the chamber.
 17. The case as claimed in claim 12,characterized in that said compression member comprises, in addition, apositioning ring (52) inserted between said spring and one of the wallsof the chamber.
 18. The case as claimed in claim 13, characterized inthat said compression member comprises, in addition, a positioning ring(52) inserted between said spring and one of the walls of the chamber.